Fixed wing aircraft typically land at airports with a reasonable level of lighting. Nevertheless, it is desirable to maintain their landing lights in an operable condition. Unlike fixed-wing aircraft, helicopters are frequently called on to land in remote areas, at night and under conditions of inadequate lighting or poor visibility. It is vitally important to land on a relatively flat surface and to avoid obstructions such as trees, wires or the like that might be struck by a rotary blade. It is also important for a pilot to judge the distance to the ground and to set the aircraft down gently to avoid damage to the aircraft and/or himself or any passengers. For these reasons, adequate lighting is essential.
Accordingly, it is presently believed that there may be a relatively large commercial market for a landing light fault detector or annunciator for fixed wing and rotary wing aircraft in accordance with the present invention. There should be a demand, because such annunciators warn a pilot whenever there is a fault in a landing light, which could make it extremely difficult to land in areas of limited visibility.
Further, the landing light fault annunciator in accordance with the present invention indicates a fault whether or not the landing light switch is in an on-position. In effect, a warning is given at any time that the battery switch is on. A still further feature of the present invention resides in allowing the landing light switch to complete a circuit to ground even though the landing light or lights are typically illuminated by about 18 to 32 volts. This feature reduces the likelihood of overheating in the wires that pass through the collective control arm to a switch which is located at the far end thereof if a ground fault occurs in the wire.
A still further advantage of the annunciator in accordance with the present invention resides in a flasher circuit that can be used to flash the landing light on and off for identification of the helicopter during flight or a landing maneuver. This helps other pilots to visually see and avoid the helicopter in flight and helps air traffic controllers to spot the helicopter when approaching an airport.